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Topic: Fermi Paradox Solutions (Read 4154 times)

The Fermi paradox or Fermi's paradox, named after physicist Enrico Fermi, is the apparent contradiction between the lack of evidence and high probability estimates for the existence of extraterrestrial civilizations. The basic points of the argument, made by physicists Enrico Fermi (1901–1954) and Michael H. Hart (born 1932), are:

There are billions of stars in the galaxy that are similar to the Sun, many of which are billions of years older than Earth. With high probability, some of these stars will have Earth-like planets, and if the Earth is typical, some might develop intelligent life. Some of these civilizations might develop interstellar travel, a step the Earth is investigating now. Even at the slow pace of currently envisioned interstellar travel, the Milky Way galaxy could be completely traversed in a few million years.

According to this line of reasoning, the Earth should have already been visited by extraterrestrial aliens. In an informal conversation, Fermi noted no convincing evidence of this, leading him to ask, "Where is everybody?" There have been many attempts to explain the Fermi paradox, primarily either suggesting that intelligent extraterrestrial life is extremely rare or proposing reasons that such civilizations have not contacted or visited Earth.

So anyone have any solutions to this? I'm leaning towards either inter-stellar civilisations aren't feasible, or we're incredibly lucky and potentially one of the first that have evolved in the galaxy. Either way, it seems that we may have to be the ones that spread intelligence throughout the galaxy, rather than waiting for it to come to us.

Brilliant! I haven't seen that before, and even though it's a subject that I'm already interested in, I still learnt a little bit from that. If you're curious about this subject, then it's a highly informative read.

I guess that I'm in the "Explanation Group 1" side. I could personally argue against all of the "Explanation Group 2" solutions without even being an expert on the subject, but it would be an interesting debate if somebody disagrees, or has a unique solution.

Based on life's evolutionary history here on Earth, I'm inclined to say: single celled life is probably relatively common because is developed almost the instant the planet was able to support it; multicellular life is relatively rare, but not super unusual because it developed within a few billion years; clever organisms are not substantially more rare than multicellular life because we have many examples of it (elephants, octopi, dolphins, various primate and bird species, etc); and technologically capable life is exceptionally rare because it requires many factors beyond intelligence to line up. I can't imagine dolphins ever developing technology millions of years down the line because of the simple fact that they have no means of fine manipulation. So, to put it in terms of the waitbutwhy article, there is one filter with the development of multicellular life and another at technology development.

I don't really buy into the argument that all the intelligent life in the universe has gone extinct. I think people underestimate how resilient we are as a species. I doubt even a total collapse of civilization would lead to our extinction; we would just be set back 10000 years, which is not long at all in the scope of evolutionary history.

IMO intelligence is probably not the great filter. Multiple vastly different species have come fairly close. Maybe it does not happen on most planets but I think surely it would happen on a lot of them. Also the time gap between complex life and humans was not that long. Things happened pretty quick after the first land life.

I still wonder if first life could have been one of the great filters. It seemed to happen pretty quick but not absolutely instantly, from that timeline. If there were 10 unlikely things that had to happen on a given planet, they would space them selves fairly evenly though the history, and even if life only happened in one of a billion universes, it could have been crammed fairly near the start by the other 9 unlikely events that had to follow, even if they were only moderate unlikelyhoods.. so long as only one in several passed that specific filter.

Another reason I still wonder about first life being one of the great filters is that all life we have discovered so far appears to have had the same origin. We could any day find a totally independent genesis on earth some day, and then know for sure that there is nothing uncommon about life starting.

In very broad terms, the fact that neither the geologic record, nor the surface of the solar system objects we have explored, shows any signs of anyone ever being here, combined with the observation of no artificial structures or signals elsewhere in the galaxy, would suggest a solution where intelligent life forms crossing interstellar distances are rare. Filters of all sorts might have lead to that result.

One potential filter that in my view gets too little publicity in this discussion is the stability of planetary surface environments. If you look at Mars and Venus, both worlds had times when they were much more likely to be habitable than they are today. Not so the Earth: here, different feedback processes conspire to keep the surface conditions more or less stable, which has allowed billions of years of constant evolution for its life-forms. As our neighboring planets suggest, most planets might not get that (and life thus never evolves beyond the simplest forms). There is no reason why, say, the carbon cycle, the albedo feedback, the mantle heat production, the solar constant, and the position of the atmospheric cold trap should have an evolving equilibrium which is just right to keep surface oceans stable over billions of years, until an intelligent species pops up. We take this for granted, but if that wouldn't be the case here, we wouldn't exist.

The universe is big enough that this might plausibly have happened elsewhere too, so I do think there are ETIs out there, they are just billions of light years away (typically). The only way to ever contact them might be wormholes. Two species which expand their respective wormhole networks into the same space-time region might able to detect each other (as some exclusion rules must apply to wormhole networks to protect causality, leading to wormhole collapses) and eventually enter into contact. But species which do not have their own wormhole networks will be protected by anonymity provided simply by the vastness of the universe.

My own current opinion is that there are multiple filters, great or not, that collectively reduce the number of outward-expansion-oriented ETI civilizations existing at any one time to a very low number, possibly zero.

The first great filter would be the "Rare Earth" hypothesis, that the combination of circumstances needed to provide a suitable home for advanced life on the surface of a planet is very rare. From what we know and are learning, while microbial life might be very common in the Galaxy, more advanced life seems to require numerous highly improbable circumstances.

The second great filter could be the eukaryotic grade of single-celled life -- while multicellular eukaryotic life originated numerous times, eukaryotic life itself apparently originated only once in Earth's history. This, or something equivalent, appears to be necessary to allow higher organisms to develop.

The third great filter would be a sustainable technological civilization, that develops into something that can last without destruction by any of numerous causes. Once a certain technological level is reached, it becomes possible for individuals or small groups to devise ways to destroy that civilization -- for example through genetically engineered "superbugs". All it would take is ONE individual with the desire and ability, to possibly destroy that civilization. I suspect that eventually, the civilization would develop means to avoid this sort of disaster, but until then it would be vulnerable to self-inflicted destruction.

The fourth great filter (of a sort) might be an inward turn of highly advanced civilizations. The individuals comprising that civilization might quite possibly shift to a virtual reality where the individual entities could live as long as they wish, with a vastly larger range of experiences than is possible in the physical world. In which case their civilization might stop expanding outward and stay as a fixed number of "core worlds", each with a sphere of automated outposts to guard against potential physical threats.

If these great filters are real, you would indeed observe a Universe that appears empty.

My own current opinion is that there are multiple filters, great or not, that collectively reduce the number of outward-expansion-oriented ETI civilizations existing at any one time to a very low number, possibly zero.

The first great filter would be the "Rare Earth" hypothesis, that the combination of circumstances needed to provide a suitable home for advanced life on the surface of a planet is very rare. From what we know and are learning, while microbial life might be very common in the Galaxy, more advanced life seems to require numerous highly improbable circumstances.

The second great filter could be the eukaryotic grade of single-celled life -- while multicellular eukaryotic life originated numerous times, eukaryotic life itself apparently originated only once in Earth's history. This, or something equivalent, appears to be necessary to allow higher organisms to develop.

The third great filter would be a sustainable technological civilization, that develops into something that can last without destruction by any of numerous causes. Once a certain technological level is reached, it becomes possible for individuals or small groups to devise ways to destroy that civilization -- for example through genetically engineered "superbugs". All it would take is ONE individual with the desire and ability, to possibly destroy that civilization. I suspect that eventually, the civilization would develop means to avoid this sort of disaster, but until then it would be vulnerable to self-inflicted destruction.

The fourth great filter (of a sort) might be an inward turn of highly advanced civilizations. The individuals comprising that civilization might quite possibly shift to a virtual reality where the individual entities could live as long as they wish, with a vastly larger range of experiences than is possible in the physical world. In which case their civilization might stop expanding outward and stay as a fixed number of "core worlds", each with a sphere of automated outposts to guard against potential physical threats.

If these great filters are real, you would indeed observe a Universe that appears empty.

First, our SETI searches have been limited to essentially radio, and there is much from our own history to suggest that detectable output is limited to a narrow window. So if you assume a switch to largely directed communications (laser etc), then the galaxy cojld still be teeming with undetected ETIs.

Second, we are still limited to 1 instance of life. The emergence of eukaryotes took a long time but we don't really know if we were lucky or unlucky here. Multicellular life evolved many times I believe. And again on tool using intelligence, we have only one instance.

Third, on other filters (e.g. frequency of GRBs), I don't think we really know enough either.

On the rare earth hypothesis, evidence suggests planets are common, but currently we have strong observational biases against finding solar system analogues (and I'm pessimistic on the prospects for M dwarfs) so I suspect the population is high enough that even if you need a moon etc, there may still be a large number of potential systems. Basically, I don't buy this one.

The fourth great filter (of a sort) might be an inward turn of highly advanced civilizations. The individuals comprising that civilization might quite possibly shift to a virtual reality where the individual entities could live as long as they wish, with a vastly larger range of experiences than is possible in the physical world. In which case their civilization might stop expanding outward and stay as a fixed number of "core worlds", each with a sphere of automated outposts to guard against potential physical threats.

It is argued that the “generic” evolutionary pathway of advanced technological civilizations are more likely to be optimization-driven than expansion-driven, in contrast to the prevailing opinions and attitudes in both future studies on one side and astrobiology/SETI studies on the other. Two toy-models of postbiological evolution of advanced technological civilizations are considered and several arguments supporting the optimization-driven, spatially compact model are briefly discussed.

1. Evolutionary pathways of intelligent communities and ATCs

In this paper the concept of an advanced technological civilization (henceforth ATC) from the study of Ćirković & Bradbury is retained. ATCs are advanced outcomes of cultural evolution which are immune to most existential risks, barring possible universe-destroying ones (e.g., vacuum phase transition) and which have reached sufficient capacities for manipulating surrounding physical universe on large scale and with almost arbitrary precision. Thus, an ATC would reach the Type II of Kardashev's classification, based on the energy utilization; that is, an ATC would use all energy resources of its domicile planetary system. However, it is one of the purposes of the present paper to criticize the applicability of Kardashev's classification, which I believe is of very limited value in the real SETI effort and is partially misleading. ATCs as discussed here have some of the general trademarks of the posthuman civilization envisaged by diverse authors such as Stapledon, Huxley, Bostrom or Kurzweil. In other word, posthuman civilization would be a realization of ATC in the specific environment of the Solar System. This does not automatically mean that all characteristics often cited in relation to the concept of posthumanity need to apply (or even are reasonable to expect).

[...]

2. Two basic models

Two basic models listed below are undoubtedly oversimplified and extreme, but their consideration will enable easier discussion of more complex and more realistic models which will contain a mixture of these two prototypes.

2.1. “The Empire-State”

This is the classical “expand-and-colonize” model. Limits to growth are soft and to be easily overcome. Expansion is virtually unlimited, even when faced with the limits of physical eschatology. Typical ATC spreads out among the stars, utilizing resources in a large spatial volume, and increasing the number of observers indefinitely or at least for astrophysically relevant duration. This model essentially corresponds to Kardashev’s Type III civilizations or the ascent towards Type III analogs.

2.2. “The City-State”

This is the “Olympian perfection” model. Limits to expansion and growth are hard and the optimization of all activities, most notably computation is the existential imperative. Moreover, some of the limits are internalized, i.e. an advanced civilization willingly imposes some of the limits on the expansion. Expansion beyond some critical value will tend to undermine efficiency, due both to latency, bandwidth and noise problems. A typical ATC utilizes resources of its domicile planetary system and – possibly, but not really necessarily – other nearby planetary systems, conceivably by bringing resources back home instead of truly colonizing them. Instead, the future evolution of an ATC will be more and more optimization-driven. In the limit of very long timescales characterizing ATC planning and strategies, it may lead to relocation in physical space. However, this need not mean relinquishing of the basic optimization-driven model, just reinstatiating it.

3. Postbiological evolution

Clearly, we know very little at present about the modes of postbiological evolution. However, even a minimal framework derived from the very meaning of “postbiological” can still be very useful. Notably, the transition to postbiological phase obviates most, if not all, biological motivations. The very definition of ecology and the relevant ecological needs and imperatives changes, leading to significant changes in other fields which have been traditionally linked to the evolutionary processes.

As an example, the imperative for filling the complete ecological niche in order to maximize one's survival chances and decrease the amount of biotic competition is an essentially biological part of motivation for any species, including present-day humans. (Here I do not presuppose that motivation is a product of consciousness, rather than, say, adaptive strategy for fitness optimization.) It would be hard to deny that this circumstance has played a significant role in colonization of the surface of the Earth. But expanding and filling the ecological niches are not the intrinsic property of life or intelligence – they are just consequences of the predominant evolutionary mechanism, i.e. natural selection. It seems logically possible to imagine a situation in which some other mechanism of evolutionary change, like the Lamarckian inheritance or genetic drift, could dominate and prompt different types of behaviour. The same applies for the desire to procreate, leave many children and enable more competitive transmission of one's genes to future generation is linked with the very basics of the Darwinian evolution. Postbiological civilization is quite unlikely to retain anything like the genetic lottery when the creation of new generations is concerned.

[...]

10. Conclusions

As much as our understanding of the conditions and social dynamics of ATCs is negligible, some of the general issues may and should be speculated upon even at the present-day stage. This is relevant for both the future of humanity and for assessing our own SETI-projects thus far. In brief, the discussion in this paper can be summarized as follows:

• The belief that an intelligent community which survives all catastrophic risks and develops advanced technology will inexorably or even likely colonize the Galaxy is an unsupported dogma essentially equivalent to the belief in Fukuyama’s mystical “Factor X” and stemming from the same naive organicism.

• Although the real set of postbiological evolutionary pathways is likely to be immensely more complex, it still makes more sense to discuss it in the framework of the compact city-state model rather than conventionally assumed empire-state model.

• Astronomical observations confirm that there are no star-powered Kardashev’s Type III civilizations in our cosmological neighbourhood, which is most plausibly explained by assuming that the measure of postbiological evolutionary pathways leading to such galactic empires is very small or vanishing.

• Transhumanist and future studies should devote more attention to the relationship between efficiency of resource utilization and the character of cultural evolution (including the observability of a particularly evolving model civilization from afar).

Since our astrophysical knowledge clearly precludes infinite expansion, it is certainly worthwhile to investigate, at least in the most general terms, logical alternatives to it. I argue that even finite expansion makes sense only within clear limits, delineated by astrophysics, postbiological evolution and even political and moral considerations. These limits do not include civilizations of Kardashev’s Type III. Thus, their absence from our astronomical observations is neither good nor bad sign as far as the future of humanity is concerned – the very concept of Type III civilization is irrelevant concept in the first place. There is no need for a frantic search for the “Great Filter”, much less for expressing pessimism vis-à-vis astrobiological mission of search for life and intelligence in the universe.

Octopuses are intelligent, and have been around for hundreds of millions of years. And yet they still haven't made the leap to civilization or mastery of technology. It would seem that the evolution of intelligence is not enough to lead to technological civilization. For that you need a whole lot of other coincidences.

In the case of the octopus even hundreds of millions of years of relative intelligence did not lead to that next level. Elephants, whales, and various other animals are intelligent too, and yet again, did not develop technology. Maybe there are millions of worlds with even intelligent life on it, but that incredible set of coincidences that is needed to make that final leap to technological civilization did not occur.

Our ancestors were just as intelligent as us going back for 50,000 or even 200,000 years, but radio technology was invented a little over a hundred years ago. The Galaxy maybe filled with alien civilizations, but we could be the only technological civilization.

I personally think that the most likely answer is that the big jump from simple life to complex life is rare. There may be (and probably are) billions of planets in our galaxy with single-celled bacteria-like life, but possibly very, very few with complex, multi-cellular life. Simple single-celled forms were the only life on Earth for some 3 billion years, and as far as I know, as yet science has not found any particular reason why more complex life should be inevitable. We do know that here on Earth, life exploded into a very wide variety of forms about 1.5 billion years ago, once complex life began.

However, even multi-cellular life isn't necessarily a guarantee that more complex animals must evolve, or that intelligence must evolve, or if it does, that it is suited to making technology. As mentioned above, dolphins (and a few other large ocean mammals) are, as far as we can tell, very intelligent - they may even have language and culture - but the ability to make technology as we use it is far beyond them. Not only do they have flippers, and not dexterous digits on their limbs, but also they live in water - using fire as a tool, let alone for smelting ore, would be an entirely alien concept to them. It's just sheer blind luck that we have intelligence, dexterous manipulating digits on our limbs, and live on land. We're not even sure how we evolved to be as intelligent as we are. Intelligence, even self-awareness, emotional responses, and tool-making aren't unique to humans, but introspection seems to be. It's an enormously complex problem.

We have been lucky in that our planet contains fairly plentiful amounts of useful, easily accessible metals. It may be possible to evolve on a planet very poor in metals, where experimentation in smelting materials would be difficult to begin with, and therefore technology would be difficult to make or improve upon.

Another item to consider is that we also been lucky in our food sources. We have several species of grains that provide large amounts of calories, that can be farmed on large scales, and can be easily stored for some period of time. We have large animals that we have tamed to do work for us and that we also use for food. This allows for higher-population societies which are more complex than hunter-gathering groups to form, and this allows for specialization. Another species that must continually hunt for food or which relies on food sources that are nutrient-poor would be at a very big disadvantage.

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"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk"There are lies, damned lies, and launch schedules." - Larry J

Our ancestors were just as intelligent as us going back for 50,000 or even 200,000 years, but radio technology was invented a little over a hundred years ago. The Galaxy maybe filled with alien civilizations, but we could be the only technological civilization.

Plus there were several civilizations that were quite advanced long before Western civilization adopted the scientific method. It is not a given that an advanced civilization of intelligent beings will develop and embrace technology.

I think all these suggested solutions are based on the wrong assumptions. They all take a planet-centered point of view. This is reasonable from the standpoint that an earthlike planet is most likely the cradle for life, but as Tsiolkovsky pointed out, "one cannot live in a cradle forever."

If they aren't living on or traveling between planets, where would they go? My idea is simply to follow the money. What parts of a star system contain the richest sources of resources and the least difficulty of extracting them? IMO, that will be the small, undifferentiated, icy bodies in the outer parts of the system. They have extremely small gravity wells, abundant hydrogen isotopes for fusion and the creation of hydrocarbons, as well as all the other organic and mineral elements required for life and industry, without having hidden cores that would sequester heavy elements to inaccessible depths.

Once a technology has mastered fusion power, they can synthesize all the materials they need from these proto-comets. Deep gravity wells such as earthlike planets and inner solar systems become inconveniences and liabilities, and provide no economic advantages. Why haven't extraterrestrials visited here? Where are they? They have gone to profitable places. Earthlike planets are backwaters for any life forms that have advanced enough to leave the cradle.

My guess is that once we start exploring the Oort Cloud we'll learn a lot more about this.

Having had a chance to think more about this issue over the past several days, my opinion has changed somewhat. My chain of thought now runs as follows:

1. The crucial turning point in the history of any Technological Civilization (TC) is when they start to move out from their home world into their home planetary system in a significant way. Species that stay on their home world will inevitably go extinct, sooner or later, due to one or more catastrophes striking their world -- most likely due to some internally generated problem. Species that move out and colonize their planetary system, and presumably quickly turn into a Kardashev Type II civilization (quickly meaning on the order of tens of thousands to a few million years), are effectively immune to existential threats. Even nearby pre-supernovas can be dealt with before they explode, either by physically moving the pre-supernova to a safe distance, or by disassembling it entirely.

2. The rate at which TCs form is unknown. It could be as high as one per year in our galaxy alone, or as low as one per million years in the entire observable Universe, or most likely somewhere in between. The actual formation rate does not really effect the following argument.

3. I assume that technological limits are set by physical laws that are close to what we already know about. No FTL travel, no breaking the Third Law of Thermodynamics, etc. There may be, and no doubt are, tweaks to known physics, but these tweaks would likely be relatively minor in nature.

4. Building a Dyson Swarm is relatively easy, technologically speaking -- we could almost do so ourselves right now. Of course the time and effort required is immense, but the required new technology is relatively minor. Conversely, high sub-light speed interstellar colonization is much more demanding in terms of required new technology.

5. This means that any TC that starts to industrialize its planetary system will fairly quickly capture almost all its resources, including almost all the emitted energy from its primary star, and all of the mass orbiting said star (and likely thousands of Earth-masses of metals from their home star, obtained using some form of star-lifting). They could use these resources to create a classical Dyson Swarm, or maybe a Matrioshka Brain (a supercomputer that uses the entire energy output of the star), or something in between these two endpoints.

6. What gets built depends on whether the individuals in the TC remain in their physical bodies, or decide to migrate to digital forms. Most likely both, with the percentage moving to digital form increasing over time (just my guess). But in any case, the TC becomes a Kardashev Type II civilization.

7. They then face the question of whether to stay put, or move out and colonize other stars. At this point they would already have hundreds of millions times the resources of a single city-planet, conveniently concentrated around a star with no major part more than a light-hour from any other major part. This is more resources than that possessed by a typical SF galactic empire that does not convert the planetary systems in its territory into Dyson Swarms. Being effectively invulnerable to external threats, they would have no compelling reason to expand further.

8. With the technology in their possession, they could easily monitor the entire rest of the galaxy for other emerging civilizations, via automated non-reproducing but durable probes in every planetary system in the galaxy, that each send periodic updates. This could probably be paid for by the equivalent of a minor Kickstarter campaign, given the size of their economy.

8. With the technology in their possession, they could easily monitor the entire rest of the galaxy for other emerging civilizations, via automated non-reproducing but durable probes in every planetary system in the galaxy, that each send periodic updates. This could probably be paid for by the equivalent of a minor Kickstarter campaign, given the size of their economy.

Would they send Berserkers to seek out life and pre-emptively destroy it before it can evolve into a threat? (That's assuming that they've solved how to ensure that their robot warriors never turn against them.)

So anyone have any solutions to this? I'm leaning towards either inter-stellar civilisations aren't feasible, or we're incredibly lucky and potentially one of the first that have evolved in the galaxy. Either way, it seems that we may have to be the ones that spread intelligence throughout the galaxy, rather than waiting for it to come to us.

The question is asked in good faith, and perhaps it is difficult to pick up the signal in the massive noise, but if you google the history of it you will see that there is nothing to solve. [Maybe Wikipedia mentions it, I have not checked.]

Apparently Fermi put what should rightly be called his Question - not to be confused with his famous "Fermi questions" - during a dinner conversation where he proceeded to answer it: we cannot (yet) know if interstellar travel is possible*. So no paradox, whether or not you accept Fermi's own answer or not. As I remember it, the "paradox" allegation followed from (was instigated as?) a political trick by one of the many Luddite US senator we have seen. And of course most people since then has been more interested in speculation than researching the question, making a 'paradox' description a suitable frame for them.

Incidentally later the same "don't (yet) know" reasoning applied to signal transmission, since SETI has not covered much of the available spectrum, coding or sky coverage. We "need more data", as per usual.

But yes, you can go on to analyse the wider context despite the data problem. Biologist consensus is that language capable intelligence is a rare trait, akin to the elephant trunk, both have evolved only once in 4 billion years. On the other hand given the short time before life evolved on Earth it seems to emerge easily. Based on biology our type of culture should be fairly rare among inhabited planets.

*) Which implies that the universal speed limit combined with astronomical distances may prohibit interstellar civilizations. Aside from relatively cheap long distance information barter and individual choice colonization, what would be the economical basis? Too costly, I would think.

On the other hand, that ROI problem does not prohibit random spread over a system and then out from the local Oort cloud to the next. Only then evolutionary divergence would tree off species well before the typical 1-2 Myrs average lifetime of larger animal (mammal) species, again resulting in questioning "a" civilization context.